HEAVY TIMBER 



x Roof Plonking 



-Dogte'n 



each Timber) 



Fig. 12. Framing at Roof. 



sides are used, the gird- 

 ers are tied together 

 longitudinally by 1-inch 

 iron dogs placed as 

 shown in Fig. 11. The 

 detail at the roof where 

 this type of construc- 

 tion is used is shown in 

 Fig. 12. 



The supporting plate 

 on a post cap should 

 be of such size that the 

 girders will have a bear- 

 ing of at least 5 lineal inches at each end, and the end of the 

 plate should not extend more than 6 inches beyond the post. 



Minimum Minimum sizes of timber for columns vary from 

 Sizes 8 inches by 8 inches in top story, to 10 inches by 



10 inches in any story, depending upon the ordi- 

 nances of different cities. In any event, the area of cross- 

 section should be sufficient to carry the load with a suitable 

 factor of safety, and also provide fire resisting qualities. 

 Square posts of a given size are nearly one-fourth stronger 

 than a round post turned from the same timber. 



Many ordinances in a measure control the size of posts by 

 limiting the length of a post of a given side dimension. The 

 Chicago Building Ordinances state that no timber post shall 

 be longer than thirty times its least side dimension. 



Post While there is a difference of opinion as to the value 

 Details of boring posts, some insurance engineers recom- 

 mend the practice of boring a 1^-inch diameter hole 

 longitudinally through the center of the stick, with 1/2-inch 

 vent holes at top and bottom. It is claimed that this precau- 

 tion will prevent damage from dry rot in timber which has not 

 been thoroughly seasoned before using. This should not serve 

 as an excuse for using material fresh from the saw, since it is 

 advisable that none but suitably seasoned timber of the best 

 quality be used in any part of the framing. 



Edges of posts should be rounded or chamfered to prevent 

 easy ignition in case of fire. The post should be left square 



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